1. Field of Invention
The invention relates to an image forming apparatus that includes an upper body and a lower body and, more particularly to, an opening and closing movement of the upper body.
2. Description of Related Art
A known image forming apparatus includes an image forming device that forms an image on a recording medium and an image reading device that reads an image on the original document. The image forming apparatus also includes an upper body and a lower body. The upper body is mounted on the lower body and connected to the lower body by a hinge. The upper body is pivoted about the hinge as a supporting point toward an open position and a close position with respect to the lower body. The image reading device is mounted in the upper body and the image forming device is mounted in the lower body. The image forming apparatus further includes a spring interposed between the upper body and the lower body. The spring urges the upper body toward the open position while an amount of deformation of the spring increases when the upper body is moved toward the close position. Strength of the spring is adjusted to a degree that the upper body is prevented from moving toward the close position by its own weight when the upper body is moved to the open position.
However, because the amount of deformation of the spring increases when the upper body is moved to the close position, a force greater than that required supporting the weight of the upper body is stockpiled to the spring. As a result, a stress that the spring imposes on the upper body becomes great, and a bigger force is required as the upper body is brought closer to the close position, thereby worsening the convenience of operation. Further the upper body is normally positioned in the close position and subjected to stress of the spring, which may cause deformation in the upper body.